Process for producing hydroxygallium phthalocyanine

ABSTRACT

A halogen-containing hydroxygallium phthalocyanine crystal showing intense diffraction peaks at Bragg angles (2θ°±0.2°) of (1) 7.7°, 16.5°, 25.1° and 26.6°; (2) 7.9°, 16.5°, 24.4°, and 27.6°; (3) 7.0°, 7.5°, 10.5°, 11.7°, 12.7°, 17.3°, 18.1°, 24.5°, 26.2°, and 27.1°; 4) 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3°; or (5) 6.8°, 12.8°, 15.8°, and 26.0° and an electrophotographic photoreceptor containing the halogen-containing hydroxygallium phthalocyanine crystal as a charge generating material are disclosed. Hydroxygallium phthalocyanine crystals are produced by reacting a gallium trihalide with phthalonitrile or diiminoisoindoline in a halogenated aromatic hydrocarbon solvent, treating the resulting halogenated gallium phthalocyanine with an amide solvent, and hydrolyzing the halogenated gallium phthalocyanine. The photoreceptor exhibits stabilized electrophotographic characteristics.

This is a division of application Ser. No. 08/108,426, filed Aug. 19,1993, now U.S. Pat. No. 5,393,881.

FIELD OF THE INVENTION

This invention relates to novel halogen-containing hydroxygalliumphthalocyanine crystals useful as a photoconductive material and a novelprocess for producing the same and an electrophotographic photoreceptorcontaining the same.

BACKGROUND OF THE INVENTION

Phthalocyanine compounds are useful as coatings, printing inks,catalysts or electronic materials. In recent years, they have beenextensively studied particularly for their use as electrophotographicphotoreceptor materials, optical recording materials and photoelectricconversion materials.

It is known that phthalocyanine compounds generally exhibit severaldifferent crystal forms depending on the process of production or theprocess of treatment and that the difference in crystal form has a greatinfluence on their photoelectric conversion characteristics. Forexample, known crystal forms of copper phthalocyanine compounds includeα-, π-, χ-, ρ-, γ-, and δ-forms as well as a stable β-form. Thesecrystal forms are known capable of interconversion by mechanical strainapplication, a sulfuric acid treatment, an organic solvent treatment, aheat treatment, and the like (see, for example, U.S. Pat. Nos.2,770,629, 3,160,635, 3,708,292, and 3,357,989). Further, JP-A-50-38543(the term "JP-A" as used herein means an "unexamined published Japanesepatent application") has a mention of the relationship between a crystalform of copper phthalocyanine and its electrophotographiccharacteristics. Besides copper phthalocyanine, application ofmetal-free phthalocyanine, hydroxygallium phthalocyanine, chloroaluminumphthalocyanine, and chloroindium phthalocyanine in various crystal formsto electrophotographic photoreceptors have been suggested.

With reference to hydroxygallium phthalocyanine crystals, JP-A-1-221459refers to the crystal obtained by acid pasting in connection toelectrophotographic characteristics.

Reported processes for preparing hydroxygallium phthalocyanine includeacid pasting of chlorogallium phthalocyanine with sulfuric acid (Bull.Soc. Chim., France, Vol. 23 (1962)) and hydrolysis using ammoniumhydroxide and pyridine (Inorg. Chem., Vol. 19, p. 3131 (1980)).

Hydroxygallium phthalocyanine can be obtained by first synthesizing ahalogenated gallium phthalocyanine and then hydrolyzing the resultinghalogenated gallium phthalocyanine by acid pasting. Known process forproducing chlorogallium phthalocyanine, for example, include (i)reaction between gallium trichloride and diiminoisoindoline (D.C.R.Acad. Sci., Vol. 242, p. 1026 (1956)), (ii) reaction between galliumtrichloride and phthalonitrile (JP-B-3-30854; the term "JP-B" as usedherein means an "examined published Japanese patent application"), (iii)reaction between gallium trichloride and phthalonitrile in butylcellosolve in the presence of a catalyst (JP-A-1-221459), (iv) reactionbetween gallium trichloride and phthalonitrile in quinoline (Inorg.Chem., Vol. 19, p. 3131 (1980), (v) reaction between gallium tribromideand phthalonitrile (JP-A-59-133551), and (vi) reaction between galliumtriiodide and phthalonitrile (JP-A-60-59354).

However, electrophotographic characteristics of the hydroxygalliumphthalocyanine obtained by acid-pasting hydrolysis of the halogenatedgallium phthalocyanine synthesized by any of the known processes aregreatly dependent on the process used for synthesizing the startinghalogenated gallium phthalocyanine. That is, even with the crystal formbeing equal, the resulting hydroxygallium phthalocyanine compounds showlarge variation in performance as an electrophotographic photoreceptor,particularly charging properties and dark decay rate, and it has beendifficult to obtain a photoreceptor with stable characteristics.

While various proposals on phthalocyanine compounds have been made todate as described above, it is still demanded to develop phthalocyaninecompounds with further improved performance properties.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a halogen-containinghydroxygallium phthalocyanine having a novel crystal form useful as aphotoconductive material for providing an electrophotographicphotoreceptor with stabilized characteristics.

Another object of the present invention is to provide anelectrophotographic photoreceptor with stabilized characteristicscontaining such a halogen-containing hydroxygallium phthalocyaninecrystal.

Still another object of the present invention is to producehydroxygallium phthalocyanine with stabilized electrophotographiccharacteristics by a process of synthesis different from theconventional ones.

The present inventors have conducted extensive investigations on therelationship between a crystal form of various phthalocyanine compoundsand electrophotographic characteristics and, as a result, theydiscovered five novel crystal forms of halogen-containing hydroxygalliumphthalocyanine compounds. They confirmed that each of these crystals isa superior photoconductive material providing an excellentelectrophotographic photoreceptor, and thus reached the presentinvention.

As a result of investigations, the present inventors have found thathydrolysis of halogenated gallium phthalocyanine synthesized by using aspecific solvent gives hydroxyphthalocyanine with stabilizedelectrophotographic characteristics, particularly sensitivity, and thuscompleted the present invention.

The present invention relates to a halogen-containing hydroxygalliumphthalocyanine crystal showing intense diffraction peaks at Bragg angles(2θ°±0.2°) of (1) 7.7°, 16.5°, 25.1° and 26.6°; (2). 7.9°, 16.5°, 24.4°,and 27.6°; (3) 7.0°, 7.5°, 10.5°, 11.7°, 12.7°, 17.3°, 18.1°, 24.5°,26.2°, and 27.1°; 4) 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3°;or (5) 6.8°, 12.8°, 15.8°, and 26.0°.

The present invention further relates to an electrophotographicphotoreceptor comprising a photosensitive layer containing theabove-mentioned halogen-containing hydroxygallium phthalocyanine crystalas a charge generating material.

The present invention still further relates to a process for producinghydroxygallium phthalocyanine comprising reacting a gallium trihalidewith phthalonitrile or diiminoisoindoline in an aromatic hydrocarbonsolvent and hydrolyzing the resulting halogenated galliumphthalocyanine.

The present invention yet further relates to a hydroxygalliumphthlocyanine having the above crystal form by the above process forproducing thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a powder X-ray diffraction pattern of the crudechlorine-containing hydroxygallium phthalocyanine crystals obtained inSynthesis Example 5.

FIG. 2 is a powder X-ray diffraction pattern of the purifiedchlorine-containing hydroxygallium phthalocyanine crystals obtained inSynthesis Example 5.

FIGS. 3 through 8 are each a powder X-ray diffraction pattern of thechlorine-containing hydroxygallium phthalocyanine crystals obtained inExamples 1 to 5 and Example 7, respectively.

FIGS. 9 to 12 each show a schematic cross section of anelectrophotographic photoreceptor according to the present invention.

FIG. 13 is a powder X-ray diffraction pattern of the hydroxygalliumphthalocyanine crystals obtained in Comparative Example 2.

DETAILED DESCRIPTION OF THE INVENTION

Halogen-containing hydroxygallium phthalocyanine according to thepresent invention can be synthesized by reacting gallium trihalide andphthalonitrile or diiminoisoindoline in an aromatic hydrocarbon solventand hydrolyzing the resulting haloganated gallium phthalocyanine.

In the present invention, halogenated gallium phthalocyanine issynthesized from gallium trihalide and phthalonitrile ordiiminoisoindoline. Phthalonitrile or diiminoisoindoline is preferablyused in an amount of at least 4 times, usually from 4 to 10 times,equivalent to gallium trihalide. The aromatic hydrocarbon solvent to beused in the reaction preferably has a boiling point of 150° C. or higherfrom the standpoint of the production rate of halogenated galliumphthalocyanine. In particular, halogenated hydrocarbon solvents, such asα- or β-chloronaphthalene, o- or p-dichlorobenzene, andtrichlorobenzene, are preferred. Of them, α- or β-chloronaphthalene ismore preferred. The aromatic hydrocarbon can be used in an amount offrom 0.2 to 20 times by weight of phthalonitrile or diiminoisoindoline.If the amount of the solvent is too small, the reaction system isdifficult to stir. Use of too much a solvent not only necessitates muchtime for the reaction but is uneconomical. Accordingly, the solvent isdesirably used in an amount of from 0.3 to 10 times by weight ofphthalonitrile or diiminoisoindoline.

The reaction can be carried out by heating at a temperature of from 100°C. up to the boiling point of the solvent in an inert atmosphere, suchas nitrogen for 2 to 40 hours.

As a gallium trihalide, gallium trichloride is preferred.

The halogenated gallium phthalocyanine thus synthesized is then washedwith a solvent. Solvents to be used preferably include amide solvents,such as DMF and NMP. The washing with a solvent is carried out bycollecting the reaction product by filtration and dispersing theresulting filter cake in an amide solvent with stirring, if desired,under heating. The washing may be effected simply by washing the filtercake with an amide solvent.

The thus obtained halogenated gallium phthalocyanine is then hydrolyzedwith an acid or a base. That is, a solution of halogenated galliumphthalocyanine in an acid or a base is poured into an appropriatesolvent to precipitate hydroxygallium phthalocyanine.

Acids which can be used for the hydrolysis include those highly capableof dissolving halogenated gallium phthalocyanine, such astrichloroacetic acid, trifluoroacetic acid, phosphoric acid,methanesulfonic acid, hydrochloric acid, sulfuric acid, and nitric acid.Sulfuric acid is particularly preferred for its high dissolving powerand ease of handling because of no fuming properties. The acid is usedin an amount usually of from 2 to 70 parts, and preferably of from 10 to50 parts by weight of halogenated gallium phthalocyanine. Thetemperature for dissolving halogenated gallium phthalocyanine rangesfrom 0° to 100° C., and preferably 5° to 80° C.

Solvents into which the halogenated gallium phthalocyanine solution ispoured include water, a mixed solvent of water and an organic solvent,and an alkali aqueous solution. The solvent is used in an amount of from2 to 70 parts, and preferably from 5 to 50 parts by weight of the acidused. In order to avoid heat generation, the solvent is preferably keptbelow 10° C.

Bases which can be used for the hydrolysis preferably include strongbases, such as ammonium hydroxide, sodium hydroxide, and potassiumhydroxide. These bases are used as an aqueous solution or a solution inan organic solvent, e.g., alcohols, pyridine, and quinoline. The base isused in an amount of at least 1 equivalent to a halogenated galliumphthalocyanine. Heating is effective for accelerating the hydrolysis.

The hydroxygallium phthalocyanine resulting from the hydrolysis containsa halogen atom. The halogen-containing hydroxygallium phthalocyanineseems to have a structural formula shown below. ##STR1## wherein Xrepresents Cl, Br or I; and n is a number greater than 0.

The resulting halogen-containing hydroxygallium phthalocyanine is thensubjected to a solvent treatment to obtain a desired crystal form.Before being put to a solvent treatment, the synthesizedhalogen-containing hydroxygallium phthalocyanine may be ground in a ballmill, a mortar, a sand mill, a kneader, etc. with a solvent (wetgrinding) or without a solvent (dry grinding).

The solvent which can be used for the solvent treatment are selectedfrom amides (e.g., dimethylformamide and N-methylpyrrolidone), esters(e.g., ethyl acetate and butyl acetate), and ketones (e.g., acetone andmethyl ethyl ketone), mixtures thereof, and mixtures of these solventsand water according to a desired crystal form.

More specifically, alcohols (e.g., methanol and ethanol), polyhydricalcohols (e.g., ethylene glycol, glycerin, and polyethylene glycol),aromatic hydrocarbons (e.g., toluene, xylene and chlorobenzene),sulfoxides (e.g., dimethyl sulfoxide), etc. are used for obtaining (1) ahalogen-containing hydroxygallium phthalocyanine crystal having intensediffraction peaks at Bragg angles (2θ°±0.2°) of 7.7°, 16.5°, 25.1°, and26.6° (see FIG. 4); amides (e.g., N,N-dimethylformamide,N,N-dimethylacetamide and N-methylpyrrolidone), organic amines (e.g.,pyridine and piperidine), sulfoxides (e.g., dimethyl sulfoxide), etc.are used for obtaining (2) a halogen-containing hydroxygalliumphthalocyanine crystal having intense diffraction peaks at Bragg angles(2θ°±0.2°) of 7.9°, 16.5°, 24.4°, and 27.6° (see FIG. 5); aromaticalcohols (e.g., benzyl alcohol), etc. are used for obtaining (3) ahalogen-containing hydroxygallium phthalocyanine crystal having intensediffraction peaks at Bragg angles (2θ°±0.2°) of 7.0°, 7.5°, 10.5°,11.7°, 12.7°, 17.3°, 18.1°, 24.5°, 26.2°, and 27.1° (see FIG. 6); amides(e.g., N,N-dimethylformamide, N,N-dimethylacetamide andN-methylpyrrolidone), acetic esters (e.g., ethyl acetate, n-butylacetate and isoamyl acetate), ketones (e.g., acetone, methyl ethylketone and methyl isobutyl), etc. are used for obtaining (4) ahalogen-containing hydroxygallium phthalocyanine crystal having intensediffraction peaks at Bragg angles (2θ°±0.2°) of 7.5°, 9.9°, 12.5°,16.3°, 18.6°, 25.1° and 28.3° (see FIGS. 3 and 8); and polyhydricalcohols (e.g., ethylene glycol, glycerin, and polyethylene glycol),etc, are used for obtaining (5) a halogen-containing hydroxygalliumphthalocyanine crystal having intense diffraction peaks at Bragg angles(2θ°±0.2°) of 6.8°, 12.8°, 15.8°, and 26.0° (see FIG. 7).

In the present invention, the X-ray diffraction pattern in themeasurement results of intensities of the Bragg angle (2θ) respect toCuKα characteristic X-ray (wavelength: 1,541 Å). The measurementcondition are as follows:

Apparatus: X-ray diffractiometer (RAD-RC produced by Rigaku K.K.)

Target: Cu (1.5450 Å)

Voltage: 40.0 KV

Stage angle: 5.00 deg

Stop angle: 40.00 deg

Step angle: 0.020 deg

The amount of the solvent to be used in the solvent treatment rangesfrom 1 to 200 parts by weight, and preferably from 10 to 100 parts byweight, per part by weight of hydroxygallium phthalocyanine.

The solvent treatment can be carried out at a temperature of from 0° to150° C., and preferably from room temperature to 100° C. If desired, thetreatment may be effected while wet grinding with grinding aids, such assodium chloride and sodium sulfate (salt cake). The grinding aid is usedin an amount of from 0.5 to 20 parts by weight, and preferably from 1 to10 parts by weight, per part by weight of the hydroxygalliumphthalocyanine.

The electrophotographic photoreceptor according to the present inventionin which the above-described halogen-containing hydroxygalliumphthalocyanine crystals are used as a charge generating material in thephotosensitive layer thereof will be explained below.

The photosensitive layer may have either a single layer structure or alaminate structure composed of a charge generating layer and a chargetransporting layer. FIGS. 9 through 12 each show a schematic crosssection of the laminate type photoreceptor according to the presentinvention. The photoreceptor of FIG. 9 comprises conductive substrate 3having provided thereon charge generating layer 1 and chargetransporting layer 2 in this order. Subbing layer 4 may be providedbetween charge generating layer 1 and conductive substrate 3 as shown inFIG. 10. Protective layer 5 may be provided on the surface of thephotosensitive layer as shown in FIG. 11. The photoreceptor of FIG. 12has both subbing layer 4 and protective layer 5.

The photoreceptor of the present invention will further be explainedbelow with particular reference to a laminate structure.

Conductive substrate 3 includes metals, e.g., aluminum, nickel,chromium, and stainless steel; plastic films having thereon a thin filmof aluminum, titanium, nickel, chromium, stainless steel, gold,vanadium, tin oxide, indium oxide, indium-tin oxide (ITO), etc.; andpaper or plastic films coated or impregnated with aconductivity-imparting agent. While not limiting, conductive substrate 3usually has a drum shape, a sheet shape, or a plate shape.

If desired, conductive substrate 3 may be subjected to various surfacetreatments as far as the image quality is not impaired. For example, itis subjected to an oxidation treatment, a chemical treatment, a coloringtreatment, or a non-specular finish, such as surface graining.

If desired, subbing layer 4 may be provided between conductive substrate3 and charge generating layer 1. Subbing layer 4 functions to blockinjection of unnecessary charges from conductive substrate 3 into aphotosensitive layer on charging of the photosensitive layer. It alsoserves as an adhesive layer for adhesion between conductive substrate 3and the photosensitive layer. In some cases, subbing layer 4 iseffective to prevent light reflection on conductive substrate 3.

Materials for constituting subbing layer 4 include polyethylene resins,polypropylene resins, acrylic resins, zirconium chelate compounds,titanyl chelate compounds, titanium alkoxides, organotitanium compounds,and silane coupling agents. Subbing layer 4 usually has a thickness offrom 0.01 to 10 μm, and preferably from 0.05 to 2 μm.

Charge generating layer 1 is composed of the halogen-containinghydroxygallium phthalocyanine crystals prepared by the above-mentionedprocess and a binder resin.

Binder resins to be used can be chosen from a broad range of insulatingresins, such as polyvinyl butyral, polyarylate resins (e.g., apolycondensate of bisphenol A and phthalic acid), polycarbonate resins,polyester resins, phenoxy resins, vinyl chloride-vinyl acetatecopolymers, polyvinyl acetate, acrylic resins, polyacrylamide resins,polyvinyl pyridine, cellulose resins, urethane resins, epoxy resins,casein, polyvinyl alcohol, and polyvinyl pyrrolidone. Organicphotoconductive polymers, such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene, can also be used.

Solvents to be used for dissolving the binder resin include methylalcohol, ethyl alcohol, n-propyl alcohol, n-butyl alcohol, benzylalcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethylketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane,tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, andtoluene. These organic solvents may be used either individually or incombination of two or more thereof.

A weight ratio of the halogen-containing hydroxygallium phthalocyaninecrystals to the binder resin is preferably from 10:1 to 1:10. Thecrystals are dispersed in the resin solution by a general means, e.g., aball mill, an attritor or a sand mill. It is essential that the crystalform of the halogen-containing hydroxygallium phthalocyanine is notchanged by dispersion. The inventors have confirmed that the crystalform is not changed by any of the abovementioned dispersion methods. Itis effective to finely disperse the crystals to a particle size of notgreater than 0.5 μm, preferably not greater than 0.3 μm, and morepreferably not greater than 0.15 μm.

Charge generating layer 1 usually has a thickness of from 0.1 to 5 μm,and preferably from 0.2 to 2.0 μm.

Charge transporting layer 2 consists of an appropriate binder resinhaving dispersed therein a charge transporting material.

Any of known charge transporting materials can be utilized. Examples ofsuitable charge transporting materials include oxadiazole derivatives,e.g., 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole; pyrazolinederivatives, e.g.,1-[pyridyl-(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline;aromatic tertiary monoamino compounds, e.g., triphenylamine anddibenzylaniline; aromatic tertiary diamino compounds, e.g.,N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine;hydrazone derivatives, e.g., 4-diethylaminobenzaldehyde1,1'-diphenylhydrazone; and α-stilbene derivatives, e.g.,p-(2,2'-diphenylvinyl)-N,N-diphenylaniline. In addition, semiconductivehigh polymers, such as poly-N-vinylcarbazole and its derivatives,polyvinylpyrene, polyvinylanthracene, polyvinylacridine,poly-9-vinylphenylanthracene, pyreneformaldehyde resins, andethylcarbazole-formaldehyde resins, may also be used. These chargetransporting materials may be used either individually or in combinationof two or more thereof.

Binder resins which can be used in charge transporting layer 2 can beselected from known binder resins, such as polycarbonate resins,polyester resins, methacrylic resins, acrylic resins, polyvinyl chlorideresins, polyvinylidene chloride resins, polystyrene resins, polyvinylacetate resins, styrene-butadiene copolymers, vinylidenechloride-acrylonitrile copolymers, vinyl chloride-vinyl acetatecopolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers,silicone resins, silicone-alkyd resins, phenol-formaldehyde resins,styrene-alkyd resins, and poly-N-vinylcarbazole resins. These binderresins may be used either individually or in combination of two or morethereof.

A suitable weight ratio of the charge transporting material to thebinder resin is from 10:1 to 1:5.

Charge transporting layer 2 usually has a thickness of from 5 to 50 μm,and preferably of from 10 to 30 μm.

If desired, protective layer 5 comprising an appropriate binder resinmay be provided on the surface of charge transporting layer 2.Protective layer 5 may contain conductive fine particles.

The present invention will now be illustrated in greater detail withreference to Synthesis Examples and Examples, but it should beunderstood that the present invention is not deemed to be limitedthereto. All the parts and percents are by weight unless otherwiseindicated.

SYNTHESIS EXAMPLE 1

To 1500 ml of α-chloronaphthalene were added 100 parts of g galliumtrichloride and 291 parts of o-phthalonitrile, and the mixture wasallowed to react at 200° C. for 4 hours in a nitrogen stream. The formedchlorogallium phthalocyanine was collected by filtration and dispersedin 1000 ml of dimethylformamide (DMF) and heated at 150° C. for 30minutes with stirring, followed by filtration. The wet cake wasthoroughly washed with methanol and dried to obtain 156 parts (44.1%) ofchlorogallium phthalocyanine crystals.

As a result of analysis, the chlorine content of the resulting crystalswas found to be 5.84% (the calculated chlorine content for C₃₂ H₁₆ N₆CaCl was 5.74%).

SYNTHESIS EXAMPLE 2

To 100 ml of α-chloronaphthalene were added 10 parts of galliumtrichloride and 29.1 parts of o-phthalonitrile, and the mixture wasallowed to react at 200° C. for 4 hours in a nitrogen stream. The formedchlorogallium phthalocyanine was collected by filtration, and the wetcake was dispersed in 100 ml of DMF and heated at 150° C. for 30 minuteswith stirring, followed by filtration. The wet cake was thoroughlywashed with methanol and dried to obtain 28.9 parts (82.5%) ofchlorogallium phthalocyanine crystals. The chlorine content of theresulting crystals was found to be 6.49%.

SYNTHESIS EXAMPLE 3

To 100 ml of o-dichlorobenzene were added 10 parts of galliumtrichloride and 29.1 parts of o-phthalonitrile, and the mixture wasallowed to react at 180.5° C. for 4 hours in a nitrogen stream. Theformed chlorogallium phthalocyanine was collected by filtration,dispersed in 100 ml of DMF, and heated at 150° C. for 30 minutes withstirring, followed by filtration. The wet cake was thoroughly washedwith methanol and dried to obtain 12.2 parts (34.6%) of chlorogalliumphthalocyanine crystals. The chlorine content of the resulting crystalswas found to be 10.09%.

SYNTHESIS EXAMPLE 4

The same procedure as in Synthesis Example 3 was repeated, except forreplacing o-dichlorobenzene with p-dichlorobenzene. After washing, 5.1parts (14.5%) of chlorogallium phthalocyanine crystals having a chlorinecontent of 9.73% were obtained.

SYNTHESIS EXAMPLE 5

Six parts of the chlorogallium phthalocyanine crystals obtained inSynthesis Example 1 were dissolved in 180 parts of concentrated sulfuricacid at 0° C., and the solution was added dropwise to 900 parts ofdistilled water at 5° C. to precipitate crystals. The crystals werethoroughly washed with distilled water. A powder X-ray diffractionpattern of the resulting crystals is shown in FIG. 1.

The crystals turned from deep green to deep blue on addition of dilutedaqueous ammonia.

The crystals were further thoroughly washed with distilled water anddried to recover 5.1 parts of chlorine-containing hydroxygalliumphthalocyanine crystals having a chlorine content of 0.35%. A powderX-ray diffraction pattern of the resulting crystals is shown in FIG. 2.

SYNTHESIS EXAMPLES 6 TO 8

Chlorine-containing hydroxygallium phthalocyanine crystals were obtainedin the same manner as in Synthesis Example 5, except for using 6 partsof each of the chlorogallium phthalocyanine crystals obtained inSynthesis Examples 2 to 4. The chlorine content was found to be 0.96%(Synthesis Example 6), 4.78% (Synthesis Example 7,) or 4.35% (SynthesisExample 8).

COMPARATIVE SYNTHESIS EXAMPLE 1

To 230 parts of quinoline were added 30 parts of 1,3-diiminoisoindolineand 9.1 parts of gallium trichloride, and the mixture was allowed toreact at 200° C. for 3 hours in a nitrogen stream. The formedchlorogallium phthalocyanine were collected by filtration, washed withacetone and methanol, and dried to obtain 28 parts of chlorogalliumphthalocyanine.

COMPARATIVE SYNTHESIS EXAMPLE 2

Phthalonitrile (29.1 parts) and 10 parts of gallium trichloride werereacted in a 300 ml flask at 300° C. for 4 hours in a nitrogen stream.The resulting blue mass was finely ground in a mortar and suspended in200 ml of DMF, followed by heat-refluxing for 1.5 hours in a nitrogenstream. The resulting chlorogallium phthalocyanine crystals werecollected by filtration and washed. The crystals were further washedwith DMF two more times and finally with 600 ml of methanol three timesand dried to obtain 25.1 parts of chlorogallium phthalocyanine crystals.

The results of elementary analysis of the resulting chlorogalliumphthalocyanine crystals were as follows. Further, the mass spectrumdetermination revealed that the chlorogallium phthalocyanine was amixture of gallium phthalocyanine compounds having 0 to 4 chlorine atomson the phthalocyanine ring thereof.

Elementary Analysis for C₃₂ H₁₆ N₈ GaCl (%): Calcd.: C: 62.22; H: 2.61;N: 18.14; Cl: 5.74 Found: C: 60.80; H: 2.43; N: 17.15; Cl: 6.95

EXAMPLES 1 TO 8

In 15 parts of a solvent shown in Table 1 below was put 0.5 part of thechlorine-containing hydroxygallium phthalocyanine crystals obtained inSynthesis Examples 5 to 8. The mixture was milled with 30 parts of glassbeads having a diameter of 1 mm for 24 hours. The crystals wereseparated, washed with methyl alcohol, and dried to obtainchlorine-containing hydroxygallium phthalocyanine crystals.

A powder X-ray diffraction pattern of the resulting hydroxygalliumphthalocyanine crystals are shown in Table 1. In Table 1, HOGaPc-Cl_(x)means chlorine-containing hydroxygallium phthalocyanine crystals.

                  TABLE 1                                                         ______________________________________                                                                        X-Ray                                         Example                Solvent  Diffraction                                   No.      HOGaPc-Cl.sub.x                                                                             Used     Pattern                                       ______________________________________                                        1        Synthesis     DMF      FIG. 3                                                 Example 5                                                            2        Synthesis     methanol FIG. 4                                                 Example 5                                                            3        Synthesis     dimethyl FIG. 5                                                 Example 5     sulfoxide                                              4        Synthesis     benzyl   FIG. 6                                                 Example 5     alcohol                                                5        Synthesis     ethylene FIG. 7                                                 Example 5     glycol                                                 6        Synthesis     DMF      the same as                                            Example 6              FIG. 3                                        7        Synthesis     butyl    FIG. 8                                                 Example 7     acetate                                                8        Synthesis     butyl    the same as                                            Example 8     acetate  FIG. 8                                        ______________________________________                                    

EXAMPLE 9

Three parts of the chlorogallium phthalocyanine crystals obtained inSynthesis Example 1 were dissolved in 90 parts of concentrated sulfuricacid at 0° C., and the solution was added dropwise 450 parts ofdistilled water at 5° C. to reprecipitate crystals. The crystals werethoroughly washed with distilled water. A powder X-ray diffractionpattern of the resulting crystals is the same as FIG. 1. The crystalswere further washed with diluted aqueous ammonia, suspended in 100 ml of2% aqueous ammonia, and stirred at room temperature for 1 hour. Onaddition of the 2% aqueous ammonia, the hue of the crystals changed fromdeep green to deep blue. The crystals were thoroughly washed withdistilled water and dried to obtain 0.5 part of hydroxygalliumphthalocyanine crystals. A powder X-ray diffraction pattern of theresulting crystals is the same as FIG. 2. To 15 parts ofN,N-dimethylformamide was added 0.5 part of the resulting hydroxygalliumphthalocyanine crystals and milled together with 30 parts of glass beadshaving a diameter of 1 mm for 24 hours. The crystals were separated,washed with methanol, and dried to obtain hydroxygallium phthalocyaninecrystals. A powder X-ray diffraction pattern of the resulting crystalsis the same as FIG. 3.

EXAMPLES 10 TO 12 AND COMPARATIVE EXAMPLES 1 TO 2

Hydroxygallium phthalocyanine crystals were obtained in the same manneras in Example 9, except for replacing the chlorogallium phthalocyaninecrystals obtained in Synthesis Example 1 with each of the chlorogalliumphthalocyanine crystals obtained in Synthesis Examples 2 to 4 andComparative Synthesis Examples 1 to 2. The hydroxygallium phthalocyaninecrystals using the chlorogallium phthalocyanine crystals in SynthesisExamples 2 to 4 and Comparative Synthesis Examples 1 to 2 correspond toExamples 10 to 12 and Comparative Examples 1 to 2, respectively. Thepowder X-ray diffraction pattern of each of the crystals of Examples 10to 12 and Comparative Example 1 was the same as FIG. 3. The powder X-raydiffraction pattern of Comparative Example 2 is shown in FIG. 13.

EXAMPLE 13

A solution consisting of 10 parts of a zirconium compound (OrgaticsZC540 produced by Matsumoto Seiyaku K.K.), 1 part of a silane compound(A 1110 produced by Nippon Unicar Co., Ltd.), 40 parts of isopropylalcohol, and 20 parts of butyl alcohol was coated on an aluminumsubstrate by dip coating and dried by heating at 150° C. for 10 minutesto form a subbing layer having a thickness of 0.5 μm.

The chlorine-containing hydroxygallium phthalocyanine crystals obtainedin Example 1 (0.1 part) were mixed with 0.1 part of a polyvinylbutyral-resin (S-Lec BM-S produced by Sekisui Chemical Co., Ltd.) and 10parts of n-butyl acetate, and the mixture was dispersed in a paintshaker together with glass beads for 1 hour. The resulting coatingcomposition was coated on the subbing layer with a wire bar No. 5 anddried by heating at 100° C. for 10 minutes to form a charge generatinglayer having a thickness of 0.15 μm. X-Ray diffractometry of thehydroxygallium phthalocyanine crystals in the coating compositionrevealed that the crystal form had not changed on being dispersed.

In 20 parts of monochlorobenzene were dissolved 2 parts of a compoundrepresented by formula (1): ##STR2## and 3 parts of a polycarbonateresin represented by formula (2): ##STR3## and the resulting coatingcomposition was coated on the charge generating layer by dip coating anddried by heating at 120° C. for 1 hour to form a charge transportinglayer having a thickness of 20 μm.

Electrophotographic characteristics of the thus preparedelectrophotographic photoreceptor were evaluated by using a flat platescanner as follows. The photoreceptor was charged to a potential of V₀(V) by a corona discharge of -2.5 μA under a normal temperature andnormal humidity condition (20° C., 40% RH). After 1 second, the darkpotential V_(DDP) (V) was measured to obtain a dark decay rate DDR(DDR=V₀ -V_(DDP) /V₀ ×100(%)). Then, the photoreceptor was exposed tomonochromatic light of 780 nm which was isolated from light emitted froma tungsten lamp by means of a monochromator and adjusted to 0.25 μmW/cm²on the surface of the photoreceptor. The initial sensitivity (dV/dE(V·cm² /erg)) was measured. The results of these measurements are shownin Table 2 below.

EXAMPLES 14 TO 22 AND COMPARATIVE EXAMPLES 3 TO 5

An electrophotographic photoreceptor was prepared in the same manner asin Example 9, except for using the chlorine-containing hydroxygalliumphthalocyanine crystals shown in Table 2. The resulting photoreceptorwas evaluated in the same manner as in Example 9. The results obtainedare shown in Table 2.

                  TABLE 2                                                         ______________________________________                                                 Charge                                                                        Generating                     dV/dE                                 Example  Material   V.sub.0 V.sub.DDP                                                                           DDR   (V · cm.sup.2 /              No.      Used       (V)     (V)   (%)   erg)                                  ______________________________________                                        Example 13                                                                             Example 1  -631    -610  3.3   298                                   Example 14                                                                             Example 2  -603    -582  3.5   245                                   Example 15                                                                             Example 3  -615    -589  4.2   240                                   Example 16                                                                             Example 4  -595    -554  6.8   196                                   Example 17                                                                             Example 5  -609    -580  4.8   213                                   Example 18                                                                             Example 6  -624    -588  5.6   268                                   Example 19                                                                             Example 7  -658    -637  3.3   157                                   Example 20                                                                             Example 8  -633    -611  3.5   154                                   Example 21                                                                             Example 11 -554    -522  5.8   236                                   Example 22                                                                             Example 12 -561    -529  5.7   251                                   Comparative                                                                            x-H.sub.2 Pc                                                                             -580    -552  4.8    53                                   Example 3                                                                     Comparative                                                                            Comparative                                                                              -576    -521  9.5   185                                   Example 4                                                                              Example 1                                                            Comparative                                                                            Comparative                                                                              -671    -638  4.9    2                                    Example 5                                                                              Example 2                                                            ______________________________________                                    

As described above, the halogen-containing hydroxygallium phthalocyaninecrystals according to the present invention each have a novel crystalform and are useful as a charge generating material for preparation ofan electrophotographic photoreceptor. An electrophotographicphotoreceptor prepared by using the halogen-containing hydroxygalliumphthalocyanine exhibits high photosensitivity with stability.

While the invention has been described in detail and with reference tospecific examples thereof, it will be apparent to one skilled in the artthat various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. An electrophotographic photoreceptor comprising aphotosensitive layer containing a halogen-containing hydroxygalliumphthalocyanine crystal showing intense diffraction peaks at Bragg angles(2θ°±0.2°) of (1) 7.7°, 16.5°, 25.1° and 26.6°; (2) 7.9°, 16.5°, 24.4°,and 27.6°; (3) 7.0°, 7.5°, 10.5°, 11.7°, 12.7°, 17.3°, 18.1°, 24.5°,26.2°, and 27.1°; 4) 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3°;or (5) 6.8°, 12.8°, 15.8°, and 26.0°.